The invention relates to test strips for the detection of substances present in liquids. More particularly, the invention relates to a firm support and at least one absorbent matrix impregnated with reagents, with the at least one matrix being attached to the support in areas outside the zone used for evaluation.
Test strips have been used for a long time for qualitative detection of various substances in solution and also, to an increasing extent, in combination with evaluation devices, for the quantitative detection of such substances. Test strips of this type consist, as a rule, of a small plastic bar with matrices or reaction zones fastened to the lower region thereof in the form of papers impregnated with reagents, films coated with reagents or special layers containing the reagent. Various methods are used for fastening the reaction zones to the support. A common method is, for example, to fasten the reaction zone by means of adhesives applied underneath the zone. The selection of adequately inert adhesives causes problems in this regard - particularly in the case of the reagents and enzymes, such as those used in clinical chemistry, which are often very sensitive. A further customary method is mechanical clamping of the reaction zones by means of plastic nets stretched over the zones (German Patent Specification 2,118,455). The impaired view of the surface of the reaction zone caused by the net is a disadvantage in this regard. During evaluation of a device, the network has a disturbing effect on the evaluation. In addition, it is difficult to prevent reaction zones, from falling out sideways during use.